An increasingly important process for delivering a functional material to a particular locus involves the use of microcapsules. As the term is used in the art, a microcapsule is a functional material encapsulated in a membrane.
An important application of microcapsules is in the medical arts. In this field of application, a functional drug is encapsulated in a membrane that is semipermeable to the drug. When the drug is administered to the host, the drug is transported across the semipermeable membrane to release the drug to the host.
While the use of microcapsules for drug administration is widely employed, the method suffers from certain shortcomings which limits its further application in this art. Specifically, the rate at which the drug is released to the patient is controlled by the rate at which the drug is transported across the semipermeable membrane. While many types of polymeric materials providing different diffusion rates can be employed as the semipermeable membrane, each membrane has a limited range of permeability which effectively controls the rate at which a drug of interest is released to the host. For many purposes, the drug release rate may be too slow or too rapid to provide the desired drug release rate.
Accordingly, there is a need in the art for more refined and structurally modified microcapsules having the ability to release drugs to a host over a wide range of preselected rates.